Federer survived a gritty Andy Roddick fightback to beat the American sixth seed 7-5 6-7 6-1 and Djokovic stayed on course for a fifth straight final appearance with a 6-4 6-4 win over Croatian wildcard Ivan Ljubicic.

Federer, who has yet to win a title this year, will play the winner of Friday's remaining quarter-final between British fourth seed Andy Murray and fifth-seeded Argentine Juan Martin Del Potro for a place in the semis.

Nadal came through an epic five-setter against Verdasco at the Australian Open in January and the seventh seed gave him another stiff test on the Mallorca native's favoured clay in the new Magic Box stadium.

Verdasco went long with a forehand to hand the first set to his Davis Cup team mate but fought back to open up a 4-0 lead in the second.

The French Open champion mounted an impressive comeback to reel off the next five games and Verdasco saved two match points on his serve before holding for 5-5.

Nadal carved out three more match points at 6-5 and only needed one of them to seal his 149th win on clay in 153 matches since the beginning of 2005.

Higher Gear

Earlier, Federer let slip a 3-0 lead in the second set tiebreak to drop his first set of the tournament against a gutsy Roddick.

But the Swiss maestro found a higher gear in the deciding set, on one point playing an extraordinary shot from the baseline between his legs with his back to the net and chasing down Roddick's drop volley to win the point.

"I could, and should, have won in straight sets but that's what happens when you play Andy sometimes," Federer told a news conference.

"I thought it was a good match. Andy served very well and I came up with some nice points and those make me happy."

Federer had never faced Roddick on clay before and improved his record against the former number one to 18 wins and two defeats going back to 2001.

Roddick, who has had six weeks off and got married in Texas last month, was not too downcast.

"There were some good things to take out of this," he said. "I've definitely felt worse going into the French Open before."

Djokovic got frustrated with himself at times against the 30-year-old Ljubicic but saved two break points in the second set and wrapped up victory on his first match point when the Croat went long with a return.